Consultation: stereo microscope stand for photomacrography

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Carmen
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Consultation: stereo microscope stand for photomacrography

Post by Carmen »

Esteemed photomacrographers:

CHALLENGE: I need a stable, solid, vertically oriented mount for my macro kit: namely an automated focus rail, modest DSLR, a couple of infinity corrected microscope objectives mounted to camera lenses. For now, just 4x and 10x, but possibly 20x at some future point. I use electronic flash with briefest possible pulse.

I have investigated various options: heavy duty copy stands, vertically mounted aluminum optical rail, vertically mounted optical post mounted on an aluminum breadboard, a sort of tombstone made from aluminum breadboards and other optomechanical parts, stereo microscope stands, etc...

Thus far, the most effective (cost-benefit) solution would seem to be a used, heavy duty stereo microscope stand with a vertical pole of 1.5 inch diameter. The general idea is to attach arca compatible clamps to the pole by means of "rod clamps". In this way, I expect my macro kit, and positioners, can be mounted solidly to the stand's pole, in the desired vertical orientation.

Image
photo' source

My questions, regarding this stereo microscope stand solution, are:

1. Overall, ¿does this stereo microscope stand solution sound plausibly adequate for stated needs?

2. In terms of vibration, ¿how would one reasonably expect this stereo microscope stand option to typically compare to a vertically mounted 66mm aluminum optical rail option? Given that both options are in equally optimum condition, sorothane feet, and so on.

3. ¿what features should I look for, in order for a stereo microscope stand to be adequate for above stated end use?

4. ¿what stereo microscope stand considerations have I missed?

5. ¿can you think of any other cost effective alternatives I have missed?

Your considered opinions and collective insight are greatly appreciated! :D

g4lab
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Post by g4lab »

One and a half inches is starting to get pretty strong and stiff especially if not too tall. It might also make a bit of difference if the vertical post is solid or tubular.

It looks to me like you are on the right track.

Pau
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Post by Pau »

Something similar but bigger is what I use. The rod is solid 25mm and it is pretty sensible to vibrations, but this is not much problem with EFSC

http://www.photomacrography.net/forum/v ... 7184#67184
Pau

Carmen
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Post by Carmen »

g4lab wrote:. . . It might also make a bit of difference if the vertical post is solid or tubular.
Thank you g4lab! your considered opinion is greatly appreciated! :D I imagine if the post, or pole, were hollow, it could be filled with sand or other material to minimize vibration, no?

Carmen
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Post by Carmen »

Pau wrote:Something similar but bigger is what I use. The rod is solid 25mm and it is pretty sensible to vibrations, but this is not much problem with EFSC . . .
Thank you Pau'! :D To be honest, the stereo microscope stand solution is inspired by your macro kit!

lothman
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Re: Consultation: stereo microscope stand for photomacrograp

Post by lothman »

Carmen wrote: 2. In terms of vibration, ¿how would one reasonably expect this stereo microscope stand option to typically compare to a vertically mounted 66mm aluminum optical rail option? Given that both options are in equally optimum condition, sorothane feet, and so on.
The deflection of rail depends on the Elastic modulus of the material (steel three times higher then alumina) and the cubed hight against the bending axis. So 66mm hight beats steel ø30 and I think the 66mm rail will be much stiffer and therefore better against vibration.

The next topic is: on a square shaped rail it is easier to mount an arca clamp than on an round rail.

So I would recommend a 100x100 alumina profile like this:
http://www.boschrexroth.com/en/xc/produ ... ents/index

where you can get a lot of connectors/accessory and mounting something like a light arm or a light reflector becomes quite easy.

regards
Lothar

Carmen
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Re: Consultation: stereo microscope stand for photomacrograp

Post by Carmen »

lothman wrote: . . . The deflection of rail depends on the Elastic modulus of the material (steel three times higher then alumina) and the cubed hight against the bending axis. So 66mm hight beats steel ø30 and I think the 66mm rail will be much stiffer and therefore better against vibration.
Thank you Lothar! So would it be correct to say that an equivalent mass of aluminum is approx' 3x less prone to vibration than steel? - at least in principle?
lothman wrote: . . . I would recommend a 100x100 alumina profile like this . . .
For an aluminum profile (or aluminum rail) to work adequately, it would seem that the trick is to minimize expensive optomechanical mounting parts: mount the focus rail as efficiently as possible, mount to base as efficiently as possible.

An aluminum rail with an arca compatible dovetail shape could couple directly to the focus rail, by means of a "back-to-back" arca compatible clamp. :D

It would be even more efficient to mount a simple arca compatible clamp directly to an aluminum rail, perhaps by means of T-slot groove and matching T-nuts.

I will continue to investigate aluminum rails, with an eye to an minimizing expensive optomechanical mounting parts. Please let me know if anything suitable occurs to you.

lothman
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Re: Consultation: stereo microscope stand for photomacrograp

Post by lothman »

Carmen wrote: Thank you Lothar! So would it be correct to say that an equivalent mass of aluminum is approx' 3x less prone to vibration than steel? - at least in principle?
I have not calculated but my feelings says this is wrong. It is not a question of mass but more of volume and its distance to the so called neutral axis. Alumina has one third of density of steele so with same mass you have three times the volume (today they make bicycle frames from alumina, larger diameter of tubes, less weight and less deflection)

What describes the resistance against deflection is the moment of inertia and of course the elasticity module of the material. I have no links in english language but this my help:

http://www.learneasy.info/MDME/MEMmods/ ... nding.html

Image

so you see increasing "d" (cubed) has the most effect. Or in other words increasing the diameter of your rail has much more effect against deflection. For vibration damping also comes in consideration, but the less movement occurs usually the lesser has to be damped.


Carmen wrote: For an aluminum profile (or aluminum rail) to work adequately, it would seem that the trick is to minimize expensive optomechanical mounting parts: mount the focus rail as efficiently as possible, mount to base as efficiently as possible.
yes that's the way to go.

Carmen wrote: An aluminum rail with an arca compatible dovetail shape could couple directly to the focus rail, by means of a "back-to-back" arca compatible clamp. :D

It would be even more efficient to mount a simple arca compatible clamp directly to an aluminum rail, perhaps by means of T-slot groove and matching T-nuts.
yep but therefore you might have to produce some custom parts.
Carmen wrote: I will continue to investigate aluminum rails, with an eye to an minimizing expensive optomechanical mounting parts. Please let me know if anything suitable occurs to you.
currently I plan to convert a Nikon Focus Block into a bellows, so carrying lens and camera with as little as possible serial interfaces.

lothman
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Re: Consultation: stereo microscope stand for photomacrograp

Post by lothman »


ChrisR
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Post by ChrisR »

What describes the resistance against deflection is the moment of inertia
Not Second Moment of Area?

Filling the extrusion with sand would be good, but it's always seemed to me to be a good place to put a few kg of lead shot (Gun cartridge pellets). And not quite as messy!

lothman
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Post by lothman »

ChrisR wrote:
What describes the resistance against deflection is the moment of inertia
Not Second Moment of Area?
yes should be the second moment of inertia, sorry for my bad translation. Also the distance to the neutral axis is very important.

https://www.youtube.com/watch?v=IyRZ0WIhCdU

Carmen
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Post by Carmen »

Esteemed Lothar and photomacrographers:

First, thank you for the clarification on the properties of aluminum. I suspected I was missing something.

Second, I was so inspired by the stand made of aluminum profiles by Volker Betz, that I spent several hours investigating this option. If you know Volker Betz, please express my gratitude for showing it, and admiration of his/her inventiveness! :D

The more I investigate this heavy aluminum profiles option, the more convincing it seems. Bosch Rexroth produces a 45x270mm profile that weighs 16.7kg/meter. This seems a plausible alternative to a breadboard base.

I found a 50x100 profile that seems to be a plausible candiate for a the stand's column. My idea is to mount arca compatible clamps can directly to the aluminum profile. And I believe this profile can be firmly secured to the base plate with the correct hardware, thus serving as a sturdy vertical column. The result may prove to be superior to a stereo microscope stand.

CrisR, I had the same idea of filling with small lead pellets, or other similar material, but this may not be necessary. With the above mentioned profiles, I calculate the mass will surpass 10kg -plus gussets, T-nuts, bolts, arca compatible clamps, stage, etc...

QUESTION: Do you think the above outlined stand made of aluminum profile is excessive? :? More than necesary for 20x, with bright continuous light? Adequate for 50x? I would hate to come up short at some future point, so prefer to error on the side of less prone to vibration. But again the need to control costs is always present.

lothman
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Post by lothman »

Carmen wrote:QUESTION: Do you think the above outlined stand made of aluminum profile is excessive? :? More than necesary for 20x, with bright continuous light? Adequate for 50x? I would hate to come up short at some future point, so prefer to error on the side of less prone to vibration. But again the need to control costs is always present.
Why not 100x100 instead of 50x100, the bigger 100x100 would give you stability in both directions, also better against torsion. For a 400mm column the price difference to 50x100 is rather small. Please keep in mind that not only the dimension of the column but also all the connections have an influence on vibrations. So proper surfaces (smooth, flat, in correct angle...) and good design of the screw connections will improve your stand. If done well a 50x lens should work fine.


Carmen sorry only in German language but the pictures may help to understand. These are some design guidelines from machine tool engineering.

http://www.tuhh.de/ft2/wo/Vorlesungen/W ... uteile.pdf

Then flanges deform under the force of a bolt and that can lead that the interface is only loaded very near around the bolt. Making a small cavity helps to distribute the load to a much greater area with higher diameter. That makes a flange design much less prone to wobbling.

AAAAAAh I uploaded a pic but had a mistake in it, can one only upload one pic a day? So on flickr:

ImageBild2 by Lothman24

ChrisR
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Post by ChrisR »

The idea of the Cavity is clear - but it never occurred to me before!

There's no actual limit on uploads, your pictures will be in your "gallery".
(See "Upload picture" then "gallery".

rjlittlefield
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Post by rjlittlefield »

If there is no cavity built into the mating surfaces, consider creating one with some hard thin material used as a shim.

--Rik

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